passed by Congress and signed by then-President George W. Bush in 2005. Within a year of opening, a large leak backed up traffic for miles, which led to more investigation into leaks that were occurring within the structure. Due to the location of the tunnel near the ocean, brackish water was able to seep into cracks within the concrete, which have had the potential to cause flooding. This was also due to the purposeful design of the concrete to withstand 50-degree temperature swings, instead of the actual 100-degree swings that are experienced in Boston. In 2007, there were 500 leaks that needed to be repaired. Corrosion of the tunnel light fixtures also became a problem as well, which was evidenced in 2011 when a light fixture crashed down onto the roadway. Between fixing the leaks and fixing corroded structures, a report in 2011 estimated that the costs could run a few hundred million dollars. See also Transportation in Boston References External links Tunnels in Boston Interstate 93 U.S. Route 1 Road tunnels in Massachusetts Tunnels completed in 2003